He's been described as "the most remarkable mind on the planet" and one of the world's "100 living geniuses." Daniel Tammet lives with high-functioning autistic savant syndrome. He's able to recite the mathematical constant Pi to over 22,500 decimal places from memory. But Tammet says that the differences between savant and non-savant minds are exaggerated. Daniel Tammet explains how his amazing mind works. Also, philosophy professor Ian Hacking on "Humans, Aliens and Autism."